Field of the Invention
The invention relates to a noise suppression technique used for mechanical apparatuses, and particularly, to a noise suppression apparatus and a fan module using the same.
Description of Related Art
In this information explosion era, electronic products have become inseparable from daily life. As technology continuously advances, various electronic products emerge and develop. In terms of development and application of personal computers, desktop personal computers (desktop PCs) were first developed. However, due to disadvantages of the desktop PCs, such as larger volume and poor portability, etc., portable electronic apparatuses that are easy to carry, such as notebook PCs and tablet PCs, were then developed.
As a portable electronic apparatus becomes lighter and thinner, number of components accommodated per unit volume increases rapidly. Accordingly, a heat dissipation apparatus is required for effectively dissipating heat generated by a heating element to the outside, so as to ensure normal operation of the portable electronic apparatus. A fan module is one of the most frequently used heat dissipation apparatuses. The fan module blows off or extracts out hot air near the heating element through a fan, so that the heat generated by the heating element is carried away by the nearby air, thereby achieving a heat dissipation effect.
However, the fan module easily produces noise when operating, and the noise will be transmitted from the fan to outside the electronic apparatus and will then be sensed by a user. A frequency of the noise generated by a common fan is approximately 500 Hz to 2000 Hz, which belongs to a middle audio frequency range, causing harshness and irritation to the user's ear.
In order to reduce the noise of the operating fan module, conventionally, the rotational speed is decreased, or foam rubber is attached to an outlet tube for absorbing the noise. However, such noise reduction methods are not suitable for the current design demand for lighter and thinner electronic apparatuses.